Material mixing device



April 23, 1968 w E R cH ET AL 3,379,419

MATERIAL MIXING DEVICE Original Filed Feb. 23, 1965 2 Sheets-Sheet l 3 v FIG] INVENTORS W/LHEL M 5/1? {CH usm v E/RICH mu/WWW W. EIRICH ET AL MATERIAL MIXING DEVICE A ril 23, 1968 Original Filed Feb. 23, 1965' 2 Sheets-Sheet 2 'IfilllwIllnwavIllIIIIIlI/llll/n vII/lmrllllllIlIllllmllpwrm United States Patent 3,379,419 MATERIAL MEXHNG DEVICE Wilhelm Eirich, Bahnhafstrasse 19, and Gustav Eirich, Walidnrnerstrasse 40, both of l-iardheim, Nordhaden, Germany Continuation of application Ser. No. 434,486, Feb. 23, 1965. This application Get. 14, 1966, Ser. No. 586,893 Claims priority, application Germany, Mar. 12, 1964, E 26,602 4 Claims. (Cl. 259-85) ABSTRACT OF THE ENCLOSURE An auxiliary stirring device, for a mixing pan, is disclosed as including a rotatable upright shaft having rod mounting means secured thereto, with substantially rectilinear rods carried by the rod mounting means and eX- tending downwardly into the mixing pan. The rods have upper fixed ends secured to the mounting means and lower free ends which are free of connection to each other.

In one embodiment of the invention, the rods diverge downwardly from a point at least substantially closer to the mounting means than to the lower free ends of the rods. In another embodiment of the invention, the rods are substantially upright and parallel to the shaft, and are disposed completely below the normal level of material in the mixing pan.

Background of the invention This application is a continuation of our application 434,486, filed Feb. 23, 1965, now abandoned.

This invention relates in general to material mixing devices, and in particular to a new and useful combination pan mixer and mixing tool particularly adaptable for use where high whirling movement of the mixing material would be apt to produce a dust formation.

The invention is directed to a pan mixer or plate mixer for mixing materials of all kinds, for example clay, chamotte, stoneware materials, glass batches, concrete, foundry molding sand, lime, sandstone materials, ores, fertilizers, tar, asphalt-containing mixtures, paint mixtures, plastics, pharmaceutical products, foods, forage, etc. The known pan mixers consist as a general rule of a horizontal pan or bowl mixer which is either maintained stationary or is rotated about a vertical or inclined axis. The mixing apparatus further includes at least one tool system which is arranged to rotate in the pan about an axis extending either concentrically or eccentrically in respect to the center line and may advantageously comprise a stirring, mixing, kneading or crushing device, or a combination thereof. A disadvantage in the known pan mixers of this type is that they have a limited throughput capacity, since the pan diameter cannot be increased at random without considerable expenditures in cost and material, and, in addition, the height of the charge of the mixing material into the mixing pan cannot be increased materially without reducing the mixing and preparation effect, respectively.

The known mixers may be of a type in which a tool comprising, for example, several rod elements are revolved at high circumferential speed about an axis which is eccentric to the centerline of the pan. The tool aids in permitting a considerable increase in the height of charge of the mixing material into the pan. Tools of this nature usually include several rods which extend parallel to the axis of rotation of the tool arranged around a circular path, and such tools are usually driven at variable or reversible circumferential speeds. Such speeds, for example, may be a multiple of the circumferential speed of the mixing tool, two to thirty times the mixing bowl speed or three to twenty times the bowl speed preferably. By using such an auxiliary tool, it is possible to obtain faster and more thorough mixing of the material and the throughput capacity can be doubled with the same processing quality compared to that of a pan mixer without such a tool. The reason for this is that the tool permits the introduction of a much greater amount of energy into the mixing material. A disadvantage in such mixer and tool combinations is, however, that they have a tendency to create a high whirling of the material, and this is particularly disadvantageous when the material has a tendency to produce dust.

In accordance with the present invention, the disadvantages of prior art pan mixers are overcome by providing a tool which may be rotated at the same high circumferential speed as the prior art devices, for example, 200 rpm, without there being a tendency to cause dust formation or high whirling of the material being mixed. With the invention, it is possible to use the rod elements of the same type or similar nature as the prior art devices, but they are arranged so that the ends adjacent the surface of the material (the upper ends) are arranged closer together than the lower ends and the rods are advantageously arranged on a conical surface. In one embodiment of the invention, the individual rods of the auxiliary tool are arranged incined or askew to the axis of rotation of the auxiliary tool so that the circumferential speed at the point where they pass through the surface of the mixing material is less than at their :bottom ends which are oriented well down into the material. In a preferred arrangement, two rod elements are advantageously arranged at diammetrically opposite locations and are set obliquely so that their upper ends converge toward the axis of the tool, and their lower ends, which are oriented toward the bottom of the pan and submerged in the material, are more widely spaced. The rod elements advantageously carry vane guide means thereon such as baffie plates which enhance the movement of the mixing material in and out of the zone covered by the rod. Bafiie plates are advantageously arranged, for example, according to the invention on the part of the rod adjacent the top so that they extend radially to the axis of rotation of the auxiliary tool to enhance the inward movement of the material at that location. At the bottoms of the rods the baflle plates are arranged to direct the material outwardly. By such a construction, it is possible to achieve a rapid introduction of the mixing material into the upper zone of the mixing material contained in the pan and a rapid discharge may be obtained at the lower portion thereof, so that vigorous circulation greatly enhancing the mixing process is achieved. The angular position of the bafile plates, their width and their height is adapted for the particular cases in accordance with the properties of the mixing materials being employed. Under some conditions, the bafile plates directing the material outwardly may be eliminated, since the materials will have a normal tendency to be directed outwardly.

In accordance with another embodiment of the invention, the rod elements of the tool are advantageously mounted on the holder such that they cross substantially at the location of the height of the material in the pan mixer. With such a construction the rods thus are closest to the axis of rotation at the surface of the material, whereas the rods, at the lower portion of the material toward the bottom of the pan, are further away from the axis of rotation. In still another embodiment, the rods are advantageously mounted on a cross member below the surface of the material, so that they rotate in the material at a selected speed well below the surface so that no whirling and stir-ring up of dust is created.

Accordingly, it is an object of this invention to provide a pan mixing device including an auxiliary tool having tool elements arranged for rotation about the axis of the tool in a manner such that they do not tend to create the whirling up of dust of the material being mixed.

A further object of the invention is to provide a combination tool mixing device and pan mixer in which the tool device includes rod elements which are arranged obliquely in the pan mixer so that the portions thereof are spaced closer together adjacent the surface of the material to be mixed and further apart at the bottom of the pan and well submerged within the material.

A further object of the invention is to provide a pan mixing device which includes two tool rod elements which are rotatable about an axis either eccentric or concentric to the pan axis and which are arranged at spaced locations about a conical surface; and wherein the rods converge upwardly from the bottom of the pan mixer and carry baffle elements for directing the material to be mixed in a desired inflow and outflow path.

A further object of the invention is to provide a tool mixer for a pan mixing device which includes tool elements advantageously arranged either below the surface of the material to be mixed or obliquely in a manner such that dust is not created from the material in the pan.

A further object of the invention is to provide a mixing device which is simple in design, rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

In the drawings:

FIG. 1 is a transverse section through a mixing pan having a mixing tool constructed in accordance with the invention;

FIG. 2 is a section taken on the line 22 of FIG. 1;

FIG. 3 is a view similar to FIG. 1 of another embodiment of the invention;

FIG. 4 is a view similar to FIG. 3 but the tool turned 90 from that indicated in FIG. 3;

FIG. 5 is a view similar to FIG. 4 but of another embodiment of the invention; and

FIG. 6 is a view similar to FIG. 1 of another embodiment of the invention.

Referring to the drawings in particular, the invention embodied therein comprises a combination of a large rotatable mixing pan or bowl generally designated 50 and a mixing tool generally designated 52 which in the embodiment illustrated is mounted for rotation about an axis eccentric in respect to the axis of rotation of the pan 50. The pan 50 is rotated by means (not shown). The tool 52 includes a shaft 3 which is rotatably journaled in an element 4 and is adapted to be connected to means (not shown) for imparting a separate rotation thereto. In the embodiment illustrated, the tool 52 is located close to the outside wall 2 of the pan mixer 50 and is slightly above the bottom wall 1 thereof.

In accordance with the invention, as indicated in FIGS. 1 and 2, the auxiliary tool 52 comprises two rod elements 5, 5 which are held in a mounting or bracket member 6 affixed to the end of the shaft 3. The rods 5, 5 are held by the mounting 6 so that they extend obliquely and that they diverge outwardly toward the bottom 1 of the pan 50.

The mounting 6 is arranged so that it is above the surface 7 of the material to be mixed. As indicated in FIG. 2, the pan 50 is rotated in the direction of the arrow 9, whereas the tool is rotated about the axis of the shaft 3 in the direction of the arrow 8.

The rods 5, 5 which may have a square, round or polygonal or any profile, carry upper bafile plates 10 which are arranged to effect a radial movement of the mixing material toward the shaft 3 of the tool. In addition, the rods 5, 5 carry lower bafile plates 11 whichare oriented to effect the radial outward movement of the mixing material at this location.

A feature of the construction is that the rods 5, 5 are advantageously arranged on a. conical surface and their upper ends, because they lie on a smaller diameter, will rotate at a much lower speed than the lower ends, and there will be very little tendency to cause a whirling of the surface 7 of the material to the extent that it would cause the rising of dust.

In. the embodiments of FIGS. 3 and 4, rod elements 5', 5' are held at their upper ends on opposite ends of a mounting bracket 6 so that they converge inwardly and cross at the center of the axis of rotation or the center of the shaft 3'. In this embodiment, the mounting bracket 6' is also arranged above the surface of the mixing material 7'. It should be noted that the rods 5 are arranged in two planes which are parallel to each other and to the axis of the tool. In the embodiment of FIGS. 3 and 4, the rods 5', 5 are spaced closely together, whereas in the embodiment of FIG. 5, the rods 5" are spaced a greater distance apart.

In the embodiment of FIG. 6, there is provided a pan mixer 54 and a tool 56. The pan mixer has a bottom surface l'and a side wall 2' and the tool 56 is rotatably mounted in a journal 4" and has a shaft 3" which is driven by a member (not shown). In this embodiment, rods 5' are held on a cross member or supporting rod 12 which is substantially horizontal and which is secured to an extension 58 of the shaft 3". The extension 58 r is great enough to insure that the rods 5' are maintained below the surface 7 of the material to be mixed. As in the other embodiment, the relative movement is imparted to the mixing pan 54 and the mixing tool 56, either by rotating the pan 54 about its centerline or by rotating the tool 56 about the center of its shaft 3", or both. In some instances, the tool 56 is advantageously arranged for rotation about the same axis of rotation as the pan 54.

In some instances, the journal member 4" may also be rotated about an axis concentric to the pan axis so that the shaft 3"" is moved around in an arc in the pan. In this instance, the shaft 3 need not be driven but will rotate naturally as the part 4" is rotated.

Thus, the invention provides a mixing device comprising a pan mixer and an auxiliary tool with individual rods which are arranged or inclined to the axis of rotation of the tool so that their circumferential speed at a point where they pass through the surface of the mixing material is less than at their bottom ends which are submerged in the material. The circumferential speed at the ends of the rods which are in the material can be twice that of the case where the rods pass through the surface of the mixing material, and thus the tool may generally operate at higher speeds than would be possible with tools of this nature heretofore. The rods may also be arranged so that they are rotated below the surface of the mixing material in which they may be oriented substantially parallel to the axis of rotation of the tool, since only the small mounting shaft of the tool will pass through the mixing material at the point of its rotation.

The rods, of course, may be arranged on either a conical surface or an X-formation, but in either event, the introduction of the mixing material into the pan is at the upper part of the rods where the rotational speed is lower and is made much easier by the invention device, and the discharge of the material at the bottom end of the auxiliary tool is accelerated, which results in a good vertical circulation of the material. This also provides, favorable conditions for the discharge of the material through a central opening (not shown) of the pan bottom. The arrangement also provides for a faster movement of the material in the upper zones into the interior of the auxiliary tool so that more mixing material passes through the tool than in the prior art devices. It has been found that auxiliary tools with two to a maximum of three rods have proved best in practice. If the rods are arranged too close together, the mixing material does not have suflicient time to get into the interior of the auxiliary tool. Normally, auxiliary tools with only two rods are best.

The effect produced by the auxiliary tool is naturally best when the mixing material is engaged twice by the rods of the auxiliary tool, namely at the inlet and at the outlet. This effect as well as the vertical circulation of the mixing material can be increased according to the invention by arranging on the rods 5, 5 the auxiliary baflles and 11. These bafiles enhance the inward movement on the part of the rods at the top and the outward movement at the portion of the rods adjacent their bottoms.

The parts of the rods at the auxiliary tool rotating in the lower zone of the mixing material at high circumferential speeds make it possible to cause a greater mixing rate of the material and to enhance the cutting, grinding, dividing, and the elimination of lumps in the material. This insures the circulation of the mixing material even in the case of hard to handle moist materials which are neither wet fluid nor dry fluid. The wear of the rods of the auxiliary tool can be easily controlled because when the auxiliary tool moves in c-ounterdirection to the direction of the rotation of the mixing pan, the material moves away from the pan wall toward the pan center, so that little or no mixing material moves between the auxiliary tool and the pan wall. The distance of the bottom ends of the rods of the auxiliary tool from the bottom of the pan can be so selected that a layer of the mixing material serving as a protective layer remains below these bottom ends and still participates in the circulation but at a somewhat lower speed. This also prevents excessive wear of the pan bottom and of the bottom ends of the rods of the auxiliary tool. The service life of the rods of the auxiliary tool can be increased by armoring them or covering them with a Verdur or tungsten carbide. The rods are thus also used at the same time to reduce lumps in the mixing materials but not to improve the circulation of the latter.

The arrangement of the rods of the auxiliary tool in an X-formation, according to FIGS. 3, 4 and 5, is particularly suitable for pan mixers with a relatively small mixing pan. Because of the smaller diameter available for the auxiliary tool it is necessary to use auxiliary tools which have a very small diameter but a correspondingly higher speed.

The embodiment of the invention indicated in FIG. 6 may include a rod assembly comprising a shaft extension 58, cross member 12, and the rod elements 5", 5". In this embodiment it is desirable that no detachable mounting of the individual rod elements 5 be provided because the detachable connections, screws, nuts, etc. could soon become unusable in the mixing material. For this purpose, the inventive construction includes a flange plate 60 which may be secured to a flange plate 62 of the shaft 3" instead of the mounting bracket 6, as in the other embodiment of FIGS. 1 and 2.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

We claim:

1. In a mixing pan for containing material to be mixed and an auxiliary stirring device, said stirring device comprising a rotatable upright shaft, rod mounting means fixed to the lower end of said shaft for rotation therewith, and plural substantially rectilinear rods carried by said mounting means and extending downwardly into said mixing pan, said rods having upper fixed ends secured to said mounting means and lower free ends free of connection to each other, said rods diverging downwardly from a point at least substantially closer to said mounting means than to the lower free ends of said rods whereby, upon rotation of said shaft, the lower ends of said rods have a peripheral speed substantially higher than the peripheral speed of the rod portion at said point; said point being below the level of said mounting means and said rods intersecting at said point.

2. In a mixing pan for containing material to be mixed and an auxiliary stirring device, said stirring device comprising a rotatable upright shaft, rod mounting means fixed to the lower end of said shaft for rotation therewith, and plural substantially rectilinear rods carried by said mounting means and extending downwardly into said mixing pan, said rods having upper fixed ends secured to said mounting means and lower free ends free of connection to each other, said rods diverging downwardly from a point at least substantially closer to said mounting means than to the lower free ends of said rods whereby, upon rotation of said shaft, the lower ends of said rods have a peripheral speed substantially higher than the peripheral speed of the rod portion at said point; means rotatably mounting said shaft to extend downwardly from above said mixing pan, said rods being held by said mounting means so that the portions which extend through the surface of the material are closer to the center of rotation of said shaft than the lower portions which extend downwardly toward the bottom of said mixing pan; and means on at least one of said rods adjacent the bottom and top portions thereof for directing mixing material inwardly in respect to the center of rotation of said rods at the top of the surface of the material being mixed, and outwardly in respect to the center of rotation of said rods adjacent the bottom of said mixing pan.

3. In a mixing pan and auxiliary stirring device, as claimed in claim 2, said last-named means comprising a baffle member.

4. In a mixing pan for containing material to be mixed and an auxiliary stirring device, said stirring device comprising a rotatable upright shaft, rod mounting means fixed to the lower end of said shaft for rotation therewith, and plural substantially rectilinear rods carried by said mounting means and extending downwardly into said mixing pan, said rods having upper fixed ends secured to said mounting means and lower free ends free of connection to each other, said rods diverging downwardly from a point at least substantially closer to said mounting means than to the lower free ends of said rods whereby, upon rotation of said shaft, the lower ends of said rods have a peripheral speed substantially higher than the peripheral speed of the rod portion at said point; said pan being rotatable about a vertical axis; at least one main mixing tool extending into said pan and rotatable about an axis parallel and eccentric to the axis of rotation of said pan; said auxiliary tool being rotatable about another axis parallel and eccentric to the axis of rotation of said pan and spaced from the axis of rotation of said main mixing tool.

References Cited UNITED STATES PATENTS 877,087 1/1908 Kennedy 259-108 3,215,412 11/1965 Kindler 259179 FOREIGN PATENTS 508,05 9 10/1920 France. 265,073 2/ 1927 Great Britain. 121,881 6/1948 Sweden.

ROBERT W. JENKINS, Primary Examiner. 

